I don't know how he does it but I've done similar to what he described & what tends to happen is that players sometimes run a deficit or surplus where they get more or less gold than others because they got better/worse items one or more sessions backyours has a HUGE flaw though...
lets say 5 players find a +2 longsword worth 8,000gp and a ring of prot worth 2,000 gp and 4 scrolls/potions each worth 100gp and 6 gems worth 25gp each and 400gp in coins... grand total 10,950gp... divide by 5 and that is 2,190gp each... BUT one item alone is worth 8,000. So nobody gets the +2 longsword.
if you sell it for half value (4,000 gp) you just lowered EVERYONE's share from 2190gp to 1,390gp... but now that ring of prot is too much for anyone to take by 650gp (maybe someone has 650gp but if not) that means got to sell that for 1,000gp and that brings each share down to 1,190 gp.
Your way just cost the party 5,000gp of value... but MORE important the use of the fighter having the +2 long sword hitting more often for more damage (aka improving odds of every fight) and the cleric can't have the +1 AC and Saves that again would improve odds of fight
in order to make it seem fair your party is making every adventure harder on themselves